Telephone



(N-o Model.)

J. C. LUDWIG. TELEPHONE. No, 428,174- Patented May ZO, 1890.r

@lll 111-11-.-

UNITED STATES PATENT OFFICE.

JOHN C. LUDWIG, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR OF .ONE-HALF TOA. C. PAULSELL AND MARTIN CORCORAN, OF SAME PLACE, AND T. C. COOGAN ANDH. T. COMPTON, OF OAKLAND, CALIFORNIA.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 428,174, dated May 20,1890.

Application filed July 6, 1889. Serial No. 316,712. (No model.)

To @ZZ whom it may concern,.-

Be it known that I, JOHN C. LUDWIG, of the city and county of SanFrancisco, State of California, have invented an Improvement inTelephones; and I hereby declare the following to be a full, clear, andexact description of the same.

My invention relatesl to that class of telephones in which a diaphragmoperates against 1o the armature of a magnet to induce a current overthe line-wire; and my invention consists, essentially, in a hollowsounding frame or box, to which the mouth-piece is attached, the

.back of said frame or box forming the diaphragm, which acts upon thearmature of the magnet.

My invention further consists in the combination, with a suitablediaphragm, of the particular' arrangement of armature and mag- 2o nethereinafter described; and my invention consists in the novelarrangement and combination of the hollow frame forming a sounding-boxwith a mouth -piece in its front, the back Wall serving as a diaphragm,the magz 5 net, the bobbins thereof, the armature of the magnet, and thearm of the armature resting against the back wall of the sounding-box,all as hereinafter fully described, and speciiically pointed out in theclaim.

3o The object of my invention is to materially increase the efficiencyof the telephone by increasing the loudness and distinctness of thesound transmitted. l

Referring to the accompanying drawings 3 5 for a more completeexplanation of my invention, Figure l is a perspective view of mytelephone, the casing A being vertically cut away to show the interiorparts. Fig. 2 is a vertical section of my telephone.

A is the casing of the telephone. Y

B is the sounding-box or hollow frame, made of any suitablematerial-wood or thin sheet metal-as may be desired. This soundingbox orhollow frame is made with complete 4 5 front, back, sides, and ends, andinto the front center of it is let the speaking-tube or mouthpiece C.The back wall b of the sounding box or frame forms the diaphragm of thetelephone. Mounted on a cross-support D, back of the sounding-box, isthe magnet E, having 5o the wire-Wound bobbins e.

F is the armature for the magnet, arranged on the face of the bobbinsand supported by a suitable standard f, and'fromthis armature extendsforwardly the arm G, the end of which rests in contact with the backwall or diaphragm b of the sounding box or frame.

I-I are the wires of the bobbins, one of which is the line-wire and theother the ground-wire, it not being intended in this telephone to use 6oany relay-battery at all. I have here shown these wires one to beconnected with the post I and the other to be connected with the post J.

The sounding-box B is held in place within the casing Ain any suitablemanner, as by the blocks K.

The sounding or speaking box or frame B,

I have found by experiment serves as an airchamber, in which the soundof the voice is materially increased and acts through its 7o back wallor diaphragm b with increased power-so much so that a relay or batteryof any kind is entirely unnecessary, the current sent over the line wirebeing sufficiently strong to operate on the telephone at the other 7 5end with great power and distinctness and emitting a loudness of sound,much to be desired. The back b of the box B, acting as a diaphragm, isan extensive one, and is very sensitive, and acting against the arm G of8o the armature F produces vibrations, which serve the general purposeof efficiency, for which the instrument is intended.

I am of course aware that sounding-'boxes for increasing the volume ofsound arenot new; and I am aware that in mechanical telephones suchchambers or boxes have been used-as, for example, the' old and commonform of mechanical telephone, consisting of two tin cans and anintervening string; but 9o my invention does not lie in merely asounding-box, but in the combination of such in a magnetic telephone,whereby a better result is produced and the usually necessary relay orbattery is entirely dispensed with.

Having thus described my invention, whatI claim as new, and desire tosecure by Letters Patent, is-

In :L telephone, the Combination of the holwhieh forms the diaphragm,substantially :1s 1o low frmne forming; :L sounding-hex, the spenkhereindescribed. ing-tube or mout-h-peee connected centrally In witnesswhereof I have hereunto set; my with the front ol' said frame, thenmgnet at hand. Y 5 the beek of the frame, the hohbin'S-of the JOHN CIUDXVN,

nmguet, the arnmture of said magnet on the L face of the bobhins, :mdthe projecting :mn Titnessesz of them'nmtnre, the end of whichrestsng'ninst II. NOURSE, andin Contact with the hoek. wall of the frmne1I. C. LEN.

